Just found a great resource for open source images. Its called WikiMedia commons. It works like WikiPedia, volunteers post, edit, and manage multimedia content. The media content that then ends up on in the site library is open for any use commercial, private or otherwise.
What this means for me is a source of almost ready made artwork for the CNC machine. Many illustrations are in SVG format, vector instead of raster, and can be easily edited and resized with InkScape.
As a test I started with this original image except I got the SVG version,